In recent years, to deal with the global environmental issues, electric oil pumps are being made widely use of in automotive transmissions for compensating for a reduction in oil pressure that occurs during idle stop.
There is a case where an electric pump unit which is made by unitizing a pump part which sucks an oil (a fluid) thereinto and discharges the oil thereout and an electric motor for driving the pump part is used as a drive source for those oil pumps. In the electric pump unit, by making the pump part double as a rotating shaft of the electric motor, a reduction in the number of components, reduction in size of the electric oil pump to a compact size and reduction in production costs are realized.
In this type of electric pump units, there is an electric pump unit which is made up of a trochoid pump in which a pump part is accommodated in a pump housing and which has an outer rotor having a trochoidal tooth profile and an inner rotor which is made to mesh with the outer rotor (refer to JP-A-2001-182669). On the other hand, the electric motor is accommodated in a motor housing which is integrated to communicate with the pump housing, so as to drive the pump part by the rotating shaft which supports the inner rotor.